Gastroesophageal reflux disease (GERD) is highly prevalent in Veterans and the VA spends >$177 million yearly on outpatient prescriptions for GERD. GERD decreases the quality of life and increases the risk for other co-morbidities, and increases the likelihood that a Veteran will undergo costly diagnostic endoscopy. Obesity is associated with significantly increased risk for GERD and Veteran are disproportionately overweight and obese. Thus, the American Gastroenterology Association guidelines advise weight loss for overweight/obese people with GERD. It has long been thought that several dietary factors (acidic foods, spicy foods, mint, chocolate, caffeine and alcohol) as well as high-fat diet may precipitate GERD symptoms - none of which have borne out to close scrutiny. Much of the investigation on dietary factors has targeted total and saturated fat intake as risk factors. When data are adjusted for BMI the relationships between total or saturated fat intake and GERD are not significant. We hypothesize that a specific dietary intervention focused on carbohydrate intake will have significant efficacy to address GERD. We recently conducted a nutrition intervention utilizing a low-carbohydrate / high-fat diet in adults with Class I obesity (BMI 30.0-39.9). At baseline, 25% of subjects reported experiencing GERD symptoms (heartburn, reflux and/or indigestion) at least once a week. Over 1/3 used a proton pump inhibitor (PPI) or histamine 2 receptor antagonist (H2RA) at least once a week. At baseline, we found that subjects with GERD had significantly higher total sugar intakes (101.6 +/--50.3 vs 82.5 +/- 40.9 grams/day, p = 0.024), but not higher total fat intakes. Notably, total sugar intake was a strong predictor of having GERD symptoms (p = 0.007). Most unexpectedly, all GERD symptoms and medication use had resolved by completion of the 9-week low carbohydrate / high fat diet intervention. Moreover, reduced total sugar intake was significantly associated with improved insulin sensitivity (HOMA-IR score: r =0.37, p =0.001), independent of weight loss. In this proposal we will capitalize on these novel findings and test our overarching hypothesis that the type and/or amount of dietary carbohydrate intake contributes to GERD symptoms in obese people. Specific Hypothesis: Our preliminary findings suggest a physiological mechanism between dietary intake and GERD that may be related to type of dietary carbohydrate intake (complex vs simple carbohydrate). We hypothesize that modifying the type of dietary carbohydrate consumed - by reducing the proportion of simple carbohydrate (sugars) consumed - will reduce or resolve GERD symptoms and medication use in obese Veterans with chronic GERD. We further hypothesize that the mechanistic effects of reducing simple carbohydrate intake is related to either: a) improved dietary fiber intake and/or glycemic load, and thus, reduced amount and duration of esophageal acid exposure; and/or b) improved insulin sensitivity which would positively influence the function of key gastrointestinal hormones that regulate gastric motility and/or lower esophageal sphincter function. Aim 1: To determine effects of dietary carbohydrate consumed (amount and type) on percent time with esophageal pH < 4.0, number of reflux episodes, GERD symptoms and GERD medication use in 200 obese Veterans who have chronic high frequency of GERD symptoms. Aim 2: To assess associations between GERD resolution variables and factors related to potential mechanisms by which modifying dietary carbohydrate intake would resolve/reduce GERD in obese Veterans.